1. Field of the Invention
The present invention relates to a laser beam multiplexer for multiplexing a plurality of laser beams.
2. Description of the Related Art
As laser beams outputted from lasers such as laser diodes are coherent light having a single wavelength and being in phase, the laser beams are used in various fields such as displays and various processing apparatuses. However, higher-power laser beams have been recently desired in these fields.
One of methods of obtaining higher-power laser beams is a method of multiplexing a plurality of laser beams to increase light intensity. Examples of such a method of multiplexing a plurality of laser beams in related art include a method of superimposing laser beams by a lens, a method of multiplexing p-polarized and s-polarized laser beams (PS multiplexing), and a method of multiplexing laser beams with different wavelengths as described in Roland Diehl (Ed.) “High-Power Diode Lasers: fundamentals, Technology, Applications”, p 310, (2000) Springer-Verlag Berlin Heidelberg N.Y.
As illustrated in FIG. 9, in the method of multiplexing laser beams by a lens, a plurality of laser sources 101 are arranged in parallel, and laser beams emitted from the laser sources 101 are condensed by a lens 102 to be multiplexed.
As illustrated in FIG. 10, in the method of PS multiplexing, laser sources 101a and 101b with different polarizations are arranged so as to face a polarizing beam splitter (PBS) 103, and a p-polarized laser beam emitted from the laser source 101a is transmitted through the PBS 103, and an s-polarized laser beam emitted from the laser source 101b is reflected by the PBS 103, thereby the transmitted laser beam and the reflected laser beam are combined with each other. Thereby, the laser beams with different polarizations (which are orthogonally polarized) are multiplexed into one beam. A polarizing prism may be used instead of the PBS 103.
As illustrated in FIG. 11, in the method of multiplexing laser beams with different wavelengths, laser sources 101c and 101d with different wavelengths are arranged so as to face a dichroic mirror 104, and a laser beam with a wavelength λ1 emitted from the laser source 101c is transmitted through the dichroic mirror 104, and a laser beam with a wavelength λ2 emitted from the laser source 101d is reflected by the dichroic mirror 104, thereby the transmitted beam and the reflected beam are combined with each other.